Wildfire forces evacuations in Oklahoma City

NEW: About 600 acres and 12 structures, including two homes, are destroyed

NEW: High winds fan the blaze in the city's northwestern neighborhood

NEW:A temporary shelter has been set up in an elementary school

(CNN) -- A fire fueled by dry and windy conditions destroyed at least two homes and was threatening others in Oklahoma City Tuesday evening, causing the evacuation of a 2-square-mile area of the city, according to a state emergency management official.

Evacuations have been under way in Oklahoma City since Tuesday afternoon, with police going neighborhood to neighborhood getting people out of their homes, said Michelann Ooten, deputy director of the Oklahoma Department of Emergency Management.

A dozen structures have been destroyed, including two homes, and about 600 acres have been consumed since the blaze broke out at about 1 p.m., fire officials told CNN Oklahoma City affiliate KOCO.

Two injuries have been reported, KOCO reported. A woman who was overcome by smoke was reported to be in good condition and a firefighter was being evaluated for what may have been heat exhaustion, fire department spokesman Mark Woodard told the station.

The fire started between 50th Street NE and North Sooner Road, on the northwest side of the sprawling city, said Fire Chief Keith Bryant. The cause of the blaze has not been determined, he said.

A fire department spokesman said several hundred people have been evacuated, and the Red Cross of Central Oklahoma opened a temporary shelter at an elementary school, KOCO reported.

Strengthening winds later Tuesday added to the misery.

"We had high temperatures, but now the winds have returned with a vengeance," Ooten said. "It's sustained 15-20 mph with gusts at 25-35 mph."

Fires also broke out in Tecumseh and Pittsburg County, east of the capital city, and in Grady County to the southwest, Ooten said.

Three National Guard helicopters have been providing water drops and the state emergency operation center has been activated, Ooten said.